Ex vivo bioengineering of skeletal muscle tissue (BioArtificial Muscle, BAM) is currently aimed at two potential clinical applications following implantation in vivo: 1) to perform directed work to augment endogenous muscle force generation; and 2) to chronically secrete recombinant therapeutic proteins when the long-lived muscle fibers are genetically engineered. Tissue bioengineering requires the use of cells and an appropriate extracellular matrix such as collagen, and the design of a clinical product will necessitate the use of a FDA-approved collagen matrix. Type 1 collagens are currently available for cosmetic surgical applications, but their use in tissue bioengineering of skeletal muscle has not been optimized for either muscle force generation or therapeutic protein delivery. Collagen concentrations used to engineer human BAMs (HBAMs) from primary adult human skeletal muscle stem cells have poor viscoelastic properties and are anti-angiogenic when implanted into immunodeficient mice. The primary objective of this project is to reduce to a minimum HBAM collagen content while maintaining their structural integrity. HBAMs will be tissue engineered with varying amounts of FDA-approved collagens and their active force generation and elasticity measured in vitro. A patented Electro-Mechanical Tissue Stimulator (EMTS) device will be used to test the mechanical properties of the HBAMs and will serve as an important tool for quality control of the HBAMs as a commercial product. Adult muscle cells genetically engineered to secrete recombinant human growth hormone (rhGH) will be bioengineered into HBAMs with varying concentrations of the FDA-approved collagens and in vitro secretion rates measured. Potential commercial applications of the improved engineered BAMs include the replacement of atrophied small muscles and the long term delivery of therapeutic proteins such as recombinant human growth hormone (rhGH) systemically or insulin-like growth factor-1 (rhlGF-1) locally for the attenuation of skeletal muscle wasting disorders.